1. Field of the Invention
The present invention relates, in general, to intramedullary fixation systems and insertion instrumentation, and, more specifically, to a modular intramedullary fixation system and insertion instrumentation therefor.
2. Information Disclosure Statement
A preliminary patentability search produced the following patents which appear to be relevant to the present invention:
Chapman et al., U.S. Pat. No. 4,776,330, issued Oct. 11, 1988, U.S. Pat. No. 5,041,114, issued Aug. 20, 1991, and U.S. Pat. No. 5,190,544, issued Mar. 2, 1993, disclose modular femoral fixation systems for use in the treatment of femoral disorders resulting from injury, disease or congenital defect. Each system includes an elongated intramedullary rod 109 having a pair of transverse bores 115 through the distal end portion thereof and a pair of transverse bores 116 through the proximal end portion thereof (see, in general, FIGS. 19-22 and 25 of U.S. Pat. No. 4,776,330). In the embodiment shown in FIGS. 19 and 20 of U.S. Pat. No. 4,776,330, a diametrical slot 120 is provided at the proximal tip of the intramedullary rod 109 for engagement with appropriate insertion and extraction tools. In the embodiment shown in FIG. 22 of U.S. Pat. No. 4,776,330, a hollow sleeve 131 is detachably secured to the exterior of the proximal end portion of the intramedullary rod 109 by means of a locking screw 135 threaded into an internally-threaded bore 137 in the top of the intramedullary rod 109, thereby effectively increasing the diameter of the proximal end portion of the intramedullary rod 109.
Vives, U.S. Pat. No. 4,877,019, issued Oct. 31, 1989, discloses an intramedullary nail 1 and a beater 20 for use in inserting the intramedullary nail 1. As illustrated in FIGS. 9 and 16-18 of the Vives patent and stated at lines 20-27 of column 3 of the Vives patent, "The beater has a handle body 21 which, at the end facing towards the zone of introduction into the bone, is provided with a threaded portion 20' in which is insertable an adapter 20" onto which the nail can be threaded . . . "
Hayes, U.S. Pat. No. 5,100,404, issued Mar. 31, 1992, discloses an intramedullary nail 31 having an internally-threaded bore in its proximal end for coacting with a bolt construct (i.e., an outer bolt 63 and an inner bolt 64) used for mounting an alignment fixture 81 to the proximal end of the intramedullary nail 31 (see FIGS. 8 and 9 of U.S. Pat. No. 5,100,404), or in combination with a compression nut 62 and a compression washer 64 to provide controlled compression of a fracture (see FIGS. 6 and 7 of U.S. Pat. No. 5,100,404).
Simpson et al., U.S. Pat. No. 5,122,141, issued Jun. 16, 1992, discloses a modular intramedullary nail 10 including a base nail member 12 and an extension nail member 14 adapted to be matingly connected to the base nail member 12 by a "Morse" taper to produce an intramedullary nail of a particular length selected by a surgeon. The extension nail member 14 has a channel 46 therethrough so that a screw 42 can be used to aid the "Morse" taper in joining the base nail member 12 and extension nail member 14 together, and has transverse openings therethrough for receiving bone screws. The proximal end of the extension nail member 14 has a transverse slot 64 thereacross for allowing it to be rotated and for indicating the orientation of the transverse openings through the extension nail member 14.
Thomas, U.S. Pat. No. 5,127,913, issued Jul. 7, 1992, discloses an apparatus and method for implanting an intramedullary rod 12. The intramedullary rod 12 includes a score line 14 at its proximal end for allowing the poles of magnets 24 of an insert member 22 to be aligned with the axis of transverse holes 20 through the distal end of the intramedullary rod 12.
Intramedullary fixation systems are commonly used in treating complex fractures of long bones such as the human femur or tibia. In a typical application, an elongated rod or bar, commonly referred to as a "nail," is inserted into the intramedullary canal of a fractured femur. A typical prior art intramedullary nail may have one or more transverse apertures through the distal end thereof to allow distal bone screws or pins to be screwed or otherwise inserted through the femur and the distal end of the intramedullary nail, thereby securing the distal end of the intramedullary nail to the femur. In addition, a typical intramedullary nail may have one or more apertures through the proximal end thereof to allow proximal bone screws or pins to be screwed or otherwise inserted through the femur and the proximal end of the intramedullary nail, thereby securing the proximal end of the intramedullary nail to the femur. While the distal bone screws or pins may be inserted in a transverse orientation relative to the longitudinal axis of the femur and nail (see, for example, the bone screws 22, 24 in FIGS. 1 and 2 of Simpson et al., U.S. Pat. No. 5,122,141), it may be desired to orient the proximal bone screws or pins in various angles depending on the location of the fracture, etc. For example, to reconstruct and repair a femoral neck fracture, it might be desired to extend one or more proximal bone screws or pins through the proximal end of an intramedullary nail at compound angle substantially equal to the angle of the femoral neck for extending through the femoral neck and into the femoral head (see, for example, the bone screws 58, 60 in FIGS. 1 and 2 of Simpson et al., U.S. Pat. No. 5,122,141). On the other hand, in order to reduce and repair fractures of a femur between the proximal and distal ends thereof, it might be desired to extend one or more bone screws through the proximal end of an intramedullary nail at a downward angle (see, for example, the bone screw 16 in FIG. 1 of Thomas, U.S. Pat. No. 5,127,913).
Nothing in the known prior art discloses or suggests the present invention. More specifically, nothing in the known prior art discloses or suggests an intramedullary nail including an elongated body with a transverse slot through the proximal end thereof having contour for allowing a proximal bone screw to be inserted through the transverse slot and through the proximal end of the body with the longitudinal axis of the proximal bone screw located at an angle to the central axis of the body of the nail within a range between an acute angle on either side of a plane extending transverse to the central axis of the body of the nail.